IBAM, Universidad Nacional de Cuyo, CONICET, Facultad de Ciencias Agrarias, Almirante Brown 500, M5528AHB Chacras de Coria, Argentina; Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Cuyo, 5500 Mendoza, Argentina.
IBAM, Universidad Nacional de Cuyo, CONICET, Facultad de Ciencias Agrarias, Almirante Brown 500, M5528AHB Chacras de Coria, Argentina.
Mol Phylogenet Evol. 2019 Mar;132:243-250. doi: 10.1016/j.ympev.2018.12.006. Epub 2018 Dec 7.
Angiosperm mitochondrial horizontal gene transfer (HGT) has been widely reported during the past decades. With a few exceptions, foreign sequences are mitochondrial genes or intronic regions from other plants, indicating that HGT has played a major role in shaping mitochondrial genome evolution. Host-parasite relationships are a valuable system to study this phenomenon due to the high frequency of HGT. In particular, the interaction between mimosoid legumes and holoparasites of the genus Lophophytum represents an outstanding opportunity to discern HGT events. The mitochondrial genome of the holoparasite L. mirabile has remarkable properties, the most extraordinary of which is the presence of 34 out of 43 mitochondrial protein genes acquired from its legume host, with the stunning replacement of up to 26 native homologs. However, the origin of the intergenic sequences that represent the majority (>90%) of the L. mirabile mtDNA remains largely unknown. The lack of mitochondrial sequences available from the donor angiosperm lineage (mimosoid legumes) precluded a large-scale evolutionary study. We sequenced and assembled the mitochondrial genome of the mimosoid Acacia ligulata and performed genome wide comparisons with L. mirabile. The A. ligulata mitochondrial genome is almost 700 kb in size, encoding 60 genes. About 60% of the L. mirabile mtDNA had greatest affinity to members of the family Fabaceae (∼49% to mimosoids in particular) with an average sequence identity of ∼96%, including genes but mostly intergenic regions. These findings strengthen the mitochondrial fusion compatibility model for angiosperm mitochondrion-to-mitochondrion HGT.
过去几十年里，广泛报道了被子植物线粒体水平基因转移（HGT）现象。除了少数例外，外来序列是线粒体基因或来自其他植物的内含子区域，这表明 HGT 在塑造线粒体基因组进化方面发挥了主要作用。由于 HGT 的频率很高，宿主-寄生虫关系是研究这种现象的一个有价值的系统。特别是，含羞草类豆科植物与 holoparasite 属的共生关系为识别 HGT 事件提供了一个极好的机会。 holoparasite Lophophytum mirabile 的线粒体基因组具有显著的特性，其中最显著的是其拥有 43 个线粒体蛋白基因中的 34 个是从其豆科宿主那里获得的，令人震惊的是，多达 26 个本地同源物被替换了。然而，代表 L. mirabile mtDNA 大部分 (>90%)的基因间序列的起源在很大程度上仍然未知。由于供体被子植物谱系（含羞草类豆科植物）缺乏线粒体序列，因此无法进行大规模的进化研究。我们对含羞草属 Acacia ligulata 的线粒体基因组进行了测序和组装，并与 L. mirabile 进行了全基因组比较。A. ligulata 的线粒体基因组大小约为 700kb，编码 60 个基因。大约 60%的 L. mirabile mtDNA 与豆科植物（特别是含羞草类豆科植物）的成员具有最大的亲和力，平均序列同一性约为 96%，包括基因，但主要是基因间区域。这些发现加强了被子植物线粒体到线粒体 HGT 的线粒体融合相容性模型。
